• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1555-1558
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• 2002

This paper presents deposition and characterizations of microcrystalline silicon(${\mu}c$-Si:H) films prepared by hot wire chemical vapor deposition at substrate temperature below $300^{\circ}C$. The $SiH_4$ Concentration$[F(SiH_4)/F(SiH_4)+F(H_2)]$ is critical parameter for the formation of Si films with microcrystalline phase. At 6% of silane concentration, deposited intrinsic ${\mu}c$-Si:H films shows sufficiently low dark conductivity and high photo sensitivity for solar cell applications. P-type ${\mu}c$-S:H films deposited by Hot-Wire CVD also shows good electrical properties by varying the rate of $B_2H_6$ to $SiH_4$ gas. The solar cells with structure of Al/nip ${\mu}c$-Si:H/TCO/glass was fabricated with sing1e chamber Hot-Wire CVD. About 3% solar efficiency was obtained and applicability of HWCVD for thin film solar cells was proven in this research.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.571-575
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• 2002

Generation of electrical energy faces many problems today. Solar power converters were used to convert the electrical energy from the solar arrays to a stable and reliable power source. The object of this paper is to analyze and design DC-DC converters in a solar energy system to investigate the performance of the converters. A DC-DC converter can be commonly used to control the power flow from solar cell to load and to achieve maximum power point tracking(MPPT), DC-AC converter can also be used to modulate the DC power to AC power being applied on common utility load. A DC-DC converter is used to boost the solar cell voltage to constant 360(V) DC link and to ensure operation at the maximum power point tracking, If a wide input voltage range has to be covered a boost converter is required. In this paper, author described that simulation and experimental results of PV system contain solar modules, a DC-DC converter(boost type chopper), a DC-AC converter (3-phase inverter) and resistive loads.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.426.1-426.1
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• 2016

We report high work function Aluminum doped zinc oxide (AZO) films as insertion layer as a function of O2 flow rate between transparent conducting oxides (TCO) and hydrogenated amorphous silicon oxide (a-SiOx:H) layer to improve open circuit voltage (Voc) and fill factor (FF) for high efficiency thin film solar cell. However, amorphous silicon (a-Si:H) solar cells exhibit poor fill factors due to a Schottky barrier like impedance at the interface between a-SiOx:H windows and TCO. The impedance is caused by an increasing mismatch between the work function of TCO and that of p-type a-SiOx:H. In this study, we report on the silicon thin film solar cell by using as insertion layer of O2 reactive AZO films between TCO and p-type a-SiOx:H. Significant efficiency enhancement was demonstrated by using high work-function layers (4.95 eV at O2=2 sccm) for engineering the work function at the key interfaces to raise FF as well as Voc. Therefore, we can be obtained the conversion efficiency of 7 % at 13mA/cm2 of the current density (Jsc) and 63.35 % of FF.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.196-200
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• 2005

In this work, we investigated simple Aㅣ/TCO/a-Si:H(n)/c-Si(p)/Al hetero-junction solar cells prepared by low temperature processes, unlike conventional thermal diffused c-Si solar cells. a-Si:H/c-Si hetero-junction solar cells are processed by low temperature deposition of n-type hydrogenated amorphous silicon (a-Si:H) films by plasma-enhanced chemical vapor deposition on textured and flat p-type silicon substrate. A detailed investigation was carried out to acquire optimization and compatibility of amorphous layer, TCO (ZnO:Al) layer depositions by changing the plasma process parameters. As front TCO and back contact, ZnO:Al and AI were deposited by rf magnetron sputtering and e-beam evaporation, respectively. The photovoltaic conversion efficiency under AMI.5 and the quantum efficiency on $1cm^2$ sample have been reported. An efficiency of $12.5\%$ is achieved on hetero-structure solar cells based on p-type crystalline silicon.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1598-1600
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• 2003

Microcrystalline silicon(c-Si:H) thin-film solar cells are prepared with intrinsic Si-layer by hot wire CVD. The operating parameters of solar cells are strongly affected by the filament temperature ($T_f$) during intrinsic layer. Jsc and efficiency abruptly decreases with elevated $T_f$ to $1400^{\circ}C$. This deterioration of solar cell parameters are resulted from increase of crystalline volume fraction and corresponding defect density at high $T_f$ The heater temperature ($T_h$) are also critical parameter that controls device operations. Solar cells prepared at low $T_h$ (<$200^{\circ}C$) shows a similar operating properties with devices prepared at high $T_f$, i.e. low Jsc, Voc and efficiency. The origins for this result, however, are different with that of inferior device performances at high $T_f$. In addition the phase transition of the silicon films occurs at different silane concentration (SC) by varying filament temperature, by which highest efficiency with SC vanes with $T_f$.

• Journal of the Korean earth science society
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• v.31 no.4
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• pp.348-353
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• 2010

The scattered light of solar radiance near the infrared ray area was observed to measure $H_2O$ and $O_2$ absorption lines. The changes of $H_2O$ and $O_2$ equivalent width were calculated on the basis of the measurement. $O_2$ equivalent width showed negative correlation with the amount of solar radiance; $O_2$ equivalent width had a tendency to diminish as the amount of the solar radiance increased and to increase as the amount of the solar radiance decreased. On the other hand, $H_2O$ equivalent width showed the positive correlation with the amount of solar radiance. Especially it was noted that the sum of equivalent width of absorption lines created by $H_2O$ and $O_2$ in a day was fairly constant. It is implied that the constant equivalent width is caused by the complementary development of photodissociation and recombination in $O_2$ and $H_2O$.

• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.217-222
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• 2011

This study examined the cooling performance of a solar heating and cooling system for an office building using the dynamic simulation program (TRNSYS). This solar heating and cooling system incorporates evacuated tube solar collectors of $204m^2$, storage tank of $8m^3$, 116.2kW auxiliary heater, single-effect $LiBr/H_2O$ absorption chiller of 20RT nominal cooling capacity. It was found that for the representing day showed peak cooling load the annual average collection efficiency of the collector was 32.9% and coefficient of performance of single-effect $LiBr/H_2O$ absorption chiller was 0.68. And the results shows for the cooling season the solar fraction of the solar heating and cooling system was 32.2% and maximal and minimal solar fraction was 63.4% for May 17.9% for July respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.431-432
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• 2008

HIT Solar Cell은 단결정 실리콘 웨이퍼가 초박막 amorphos 실리콘 층으로 싸여있는 구조이다. HIT Solar Cell에서 amorphos 실리콘의 두께와 도핑 농도는 태양전지의 효율을 결정하는 매우 중요한 요인이다. 본 논문에서는 높은 효율을 갖는 태양전지 설계를 위해 AFORS HET 프로그램을 이용하여 TCO_a-Si:H(p)_a-Si:H(i)_c-Si(n)_Al 구조를 설계했다. 후에 a-Si:H(p)의 두께와 a-Si:H(i) 의 두께를 가변하며 효율을 측정하였고, p-i-n 구조에서 n+ 층을 추가함에 따라 변하는 효율을 측정하였다. 최적화 한 결과 $V_{oc}$ = 693mV, $J_{sc}$ = 3891mA/$cm^{-2}$, FF = 8363%, $E_{ff}$ = 22.55% 의 고효율을 얻었다.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.87.2-87.2
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• 2012

H${\alpha}$ transient bright kernels may be an important diagnostic of energy conversion processes occurring in the choromosphere during flares. We observed an H${\alpha}$ kernel that occurred in AR 11263 in associated with a small flare on 2011 Autust 5th using the Fast Imaging Solar Spectrograph installed at the 1.6m New Solar Telescope of Big Bear Solar Observatory. We find that both the H${\alpha}$ line and the CaII 8542${\AA}$ line appear in emission, with a red asymmetry in that they display red wings of enhanced emission. The red asymmetry shows 5-30 km/s downward motion for 8 minutes. We determine some physical parameters by adopting the Cloud mode and discuss the physical meaning of these results.

• Solar Energy
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• v.9 no.2
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• pp.3-13
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• 1989

This study has been conducted to measure the performance of 5 thermosyphon solar water heaters suitable for Korean climate and to develop the most optimum system. Each system consists of two flat plate collectors of $4'{\times}8'$ (or three flat plate collectors of $3'{\times}6'$) connected in parallel and a storage tank of $300{\ell}$ capacity. Among the tested systems, the configuration that has two flat plate collectors of $4'{\times}8'$ and a horizontal tank-in-tank type storage unit with internal fins (C system) showed the highest performance.